🐛 Fix chunk.getModules() webpack 5 deprecation warning

[slorber]

Summary

Follow-up of the work of @RDIL for Docusaurus 2 to support Webpack 5 (facebook/docusaurus#4089)

We have a Webpack 5 deprecation warning: chunk.getModules() is deprecated and should be replaced by the chunkGraph API.

(node:38087) [DEP_WEBPACK_CHUNK_GET_MODULES] DeprecationWarning: Chunk.getModules: Use new ChunkGraph API
    at Function.getChunkGraphForChunk (/Users/sebastienlorber/Desktop/projects/docusaurus/node_modules/webpack/lib/ChunkGraph.js:1542:10)
    at Chunk.getModules (/Users/sebastienlorber/Desktop/projects/docusaurus/node_modules/webpack/lib/Chunk.js:217:21)
    at /Users/sebastienlorber/Desktop/projects/docusaurus/node_modules/react-loadable-ssr-addon-webpack-5/lib/ReactLoadableSSRAddon.js:154:26
    at Array.forEach (<anonymous>)
    at /Users/sebastienlorber/Desktop/projects/docusaurus/node_modules/react-loadable-ssr-addon-webpack-5/lib/ReactLoadableSSRAddon.js:147:17
    at Array.reduce (<anonymous>)

To help review, wasn't able to find doc about the new ChunkGraph API, but it seems it is equivalent, as getModules() use this new API now and just add a deprecation warning

	getModules() {
		return ChunkGraph.getChunkGraphForChunk(
			this,
			"Chunk.getModules",
			"DEP_WEBPACK_CHUNK_GET_MODULES"
		).getChunkModules(this);
	}

Why

Support Webpack 5 without warnings

Checklist

• Your code builds clean without any errors or warnings
• You are using approved terminology
• You have added unit tests, if apply.

Emojis for categorizing pull requests:

🐛 Bug fix (:bug:)

[slorber]

On the Docusaurus PR (facebook/docusaurus#4089), we'll be using my local fork react-loadable-ssr-addon-v5-slorber until this PR is merged / published.

Deploy preview at https://deploy-preview-4089--docusaurus-2.netlify.app/

[RDIL]

Just in case this isn't present for webpack 4

Suggested change

	this.getAssets(this.getMinimalStatsChunks(compilation.chunks, compilation.chunkGraph));
	this.getAssets(this.getMinimalStatsChunks(compilation.chunks, compilation.chunkGraph || null));

[slorber]

I don't think chunkGraph is present in webpack4, but not sure to understand why this call is needed? Do we want null instead of undefined?

[RDIL]

That's true. Just trying to avoid strict mode madness where possible, but this might not be entirely needed.